ixgbe: fix build with gcc 5
ixgbe: fix build with gcc 5

gcc 5 supports a new logical-not-parentheses warning which
ixgbe_common.c triggers, causing build failure with -Werror.
Since this source must not be modified, silence the warning instead.

Signed-off-by: Panu Matilainen <ef9891457927ceb95d483a81954cf06349274890@redhat.com>
Acked-by: Konstantin Ananyev <cbd5212b59ab42a210d72992d23a3aa17cfd3eaf@intel.com>

phermansson/dpdk,phermansson/dpdk,phermansson/dpdk,phermansson/dpdk